A. Field of the Invention.
The device of the present invention generally relates to a new and improved lancet assembly for puncturing the skin of a user to obtain a blood sample; and, more particularly, to a new and improved lancet assembly including a disposable end cap containing a one piece lancet.
B. Description of the Prior Art
Sharp pointed lancets are employed to make a puncture or penetration of a patient's skin in order to provide a small outflow of blood. Various tests may be employed with only small amounts of blood so that blood flowing from a finger prick is normally sufficient for these tests. Tests on the blood sample often include contacting a paper strip or reagent pad on a strip carrying chemistry with blood from the wound or puncture.
Lancet assemblies now available include a driving member that grips a lancet. Loading and removing a lancet from the driving member of the assembly requires extra care by the user to avoid being punctured. The lancet must be carefully gripped to avoid contact with the sharp end of the lancet. Present day concerns about communicable diseases transmitted through body fluids such as blood increases the risks of handling these lancets.
Current devices require the user to remove a protective cover from the sharp end of a lancet, and load the exposed lancet into a lancet assembly. After use of the assembly, the point of the lancet is exposed. Users of these devices, such as nurses, are repeatedly handling these used, exposed lancets and have a high risk of puncture by a used lancet and resultant exposure to contamination through the blood on the lancet.
Some designs of lancets include a end cap with the sharp end of the lancet contained within the end cap after use, and the opposite end of the lancet sticking out of the end cap. Upon removal of the end cap after use, it is possible for the user to be stuck with an infected lancet simply by pressing on the exposed end of the lancet thereby moving the sharp end of the lancet out of the end cap. This risk is especially high for professional users such as nurses who place used lancets in their pockets. At the end of the day the nurses reach into their pockets and pull out used items including lancets. Upon reaching into his or her pocket, the nurse can press the back end of a lancet thereby exposing the contaminated sharp point.
One example of a known lancet is illustrated in U.S. Pat. No. 3,030,959. The lancet of this patent includes a spindle designed for housing a replaceable magazine containing a stock of needles. A feeding device for feeding a needle to be used is also disclosed. After a needle is used, it is maintained in the lancet until another needle from the magazine is loaded. As the new needle is advanced, the needle preceding it is ejected from the lancet. The lancet assembly of U.S. Pat. No. 3,030,959 ejects an unprotected, exposed and contaminated needle which increases the risk of puncture by the user of the lancet assembly.
A disposable needle probe package is disclosed in U.S. Pat. No. 4,637,403. The needle package is frictionally held in the medical testing system by snapping, threading or similar procedures, and it is releasable by pushing the probe package out of the medical monitoring system. Once the probe package is released from the monitoring system, however, the needle is exposed and handling can result in puncturing the skin of the user thereby exposing the user to contaminated blood.
A lancet assembly intended to be disposable with no part of the assembly reused is disclosed in U.S. Pat. No. 4,375,815. Examples of other lancet assemblies intended to be totally disposable, as opposed to disposing only the lancet, are disclosed in U.S. Pat. Nos. 4,388,925; 4,553,541; 4,449,529 and 4,535,769.
A disposable lancet defined by a plunger is disclosed in U.S. Pat. Nos. 4,712,548 and 4,738,261. After this device has been used, the lancet is exposed with the risk that someone handling the used device could be punctured by the contaminated lancet.
Lancet assemblies in which used, exposed lancets must be removed with the risk of puncture are disclosed in U.S. Pat. Nos. 4,416,279; 4,462,405; 4,442,836 and 4,469,110.
U.S. Pat. No. 4,545,376 discloses a one piece, plastic lancet consisting of a handle and a tip. Once a protective yoke is removed, the lancet tip is completely exposed and can accidentally puncture a user.
Lancet assemblies that are totally disposable with no reusable components are disclosed in U. S. Pat. Nos. 4,624,253; 4,616,649 and 4,539,988.
A lancet assembly with a lancet exposed after use is disclosed in U.S. Pat. No. 4,452,243.
Some lancet assemblies provide for the depth of penetration of the lancet into the skin of a user or patient to be adjustable. Adjustability has been accomplished in some prior art lancet assemblies by using removable end caps. Typically, prior art lancet assemblies can be used with one of two end caps each having different size holes allowing different amounts of the skin of the finger to be contacted. With a greater amount of skin fitting into the hole, the lancet can pierce deeper into the skin of the finger. With a lesser amount of skin fitting into the end cap through the hole, a shallower piercing will occur.
There is a need for a lancet assembly in which the lancet is completely contained within a portion of the lancet assembly both before and after use such that the user can dispose of the lancet without risk of puncture. There also is a need for a lancet assembly that is easily and quickly adjustable to control the depth of penetration of the lancet into the finger of a user or patient. In addition, there is a need for a lancet which is as painless as possible.